Homework Help:
Resistance, Capacitance,

this seems to be a simple question
for the diagram at http://img.photobucket.com/albums/v11/biggm/ohm.jpg [Broken]

a)the circuit has been connected a long time...what is the voltage across the capacitor?

this one i calculated and got the right answer of 6V.

b)if the battery is disconnected how long does it take to discharge the capacitor to 1/10 of its initial voltage.

i have the equation t=-RC ln (q/Q)

where R= resistance, C=capacitance, q= final charge and Q=initial charge, i have calculated the initial and final charges using q=CV and final voltage of 3/5V. Capacitance is given...what value do i use for resistance?
i can see given the answer that it should be 18/5...which is the product of the initial and final voltage although this could be coincidental....any help here??